What is the recommended dose of intranasal midazolam (benzodiazepine) for an infant with a seizure disorder?

Intranasal Midazolam Dosing for Infants with Seizure Disorder

Administer intranasal midazolam at 0.2 mg/kg (maximum 6 mg per dose) for an infant experiencing an active seizure, which can be repeated every 10-15 minutes if seizures persist. 1

Specific Dosing Parameters

• For infants under 12 months, use 0.2 mg/kg intranasal midazolam as the standard dose for acute seizure management 1, 2, 3
• The maximum single dose should not exceed 6 mg 1
• Redosing is permitted every 10-15 minutes if seizure activity continues 1
• For infants 6 months to 5 years requiring IV sedation (non-seizure contexts), doses range from 0.05-0.1 mg/kg initially, with total doses up to 0.6 mg/kg titrated slowly 4

Critical Safety Monitoring

• Respiratory monitoring is mandatory—maintain continuous oxygen saturation monitoring throughout treatment 1
• Have bag-valve-mask ventilation and intubation equipment immediately available before administering midazolam, as respiratory depression can occur 1
• The risk of apnea increases substantially when midazolam is combined with other sedatives or opioids 1
• Monitor for at least 30 minutes following administration, as apnea can occur up to 30 minutes after the last dose 5
• Be prepared to provide respiratory support regardless of administration route 1

Onset and Duration

• Onset of action occurs within 1-2 minutes after intranasal administration 5
• Peak effect is achieved within 3-4 minutes 5
• Duration of effect is 15-80 minutes, though this is shorter in infants due to faster clearance 6, 4
• Half-life in children over 12 months is 0.8-1.8 hours 4

Important Caveats About Intranasal Dosing

• Recent evidence suggests that 0.1 mg/kg intranasal midazolam is subtherapeutic—the 0.2 mg/kg dose is necessary for adequate efficacy 7
• Intranasal midazolam at 0.1 mg/kg resulted in 25% redosing rates compared to 14% with IV/IM routes, indicating inadequate dosing 7
• The 0.2 mg/kg intranasal dose has demonstrated 84-100% efficacy when seizures are less than 30 minutes duration 8
• Intranasal midazolam achieves faster seizure cessation than rectal diazepam (mean time significantly less, P=0.005) 3

Alternative Routes if Intranasal Fails

• If intranasal administration is not effective, administer intramuscular midazolam at 0.2 mg/kg (maximum 6 mg), which is the preferred alternative route based on lower redosing rates 1
• Intravenous administration at 0.05-0.1 mg/kg given over 2-3 minutes can be considered if IV access is available 1
• Rectal diazepam 0.5 mg/kg (maximum 20 mg) is an option, though absorption may be erratic 6

Essential Follow-Up Treatment

• Immediately administer a long-acting anticonvulsant after midazolam, such as phenytoin 20 mg/kg IV over 10 minutes or fosphenytoin equivalent 1
• Midazolam is rapidly redistributed and seizures often recur within 15-20 minutes without long-acting anticonvulsant coverage 1
• Have flumazenil readily available to reverse life-threatening respiratory depression, though recognize it will also counteract anticonvulsant effects and may precipitate seizure recurrence 1, 9

Common Pitfalls to Avoid

• Do not use the 0.1 mg/kg intranasal dose—this is subtherapeutic and leads to treatment failure 7
• Do not delay treatment to establish IV access—intranasal administration is faster (mean 50.6 seconds vs 68.3 seconds for rectal diazepam) 3
• Do not use intramuscular diazepam due to tissue necrosis risk—use midazolam or rectal diazepam instead 6
• Do not administer flumazenil routinely, as it reverses anticonvulsant effects—reserve only for life-threatening respiratory compromise when mechanical ventilation is unavailable 5